For a Gaussian prime
π
and a nonzero Gaussian integer
β
=
a
+
b
i
∈
ℤ
i
with
a
≥
1
and
β
≥
2
+
2
, it was proved that if
π
=
α
n
β
n
+
α
n
−
1
β
n
−
1
+
⋯
+
α
1
β
+
α
0
≕
f
β
where
n
≥
1
,
α
n
∈
ℤ
i
\
0
,
α
0
,
…
,
α
n
−
1
belong to a complete residue system modulo
β
, and the digits
α
n
−
1
and
α
n
satisfy certain restrictions, then the polynomial
f
x
is irreducible in
ℤ
i
x
. For any quadratic field
K
≔
ℚ
m
, it is well known that there are explicit representations for a complete residue system in
K
, but those of the case
m
≡
1
mod
4
are inapplicable to this work. In this article, we establish a new complete residue system for such a case and then generalize the result mentioned above for the ring of integers of any imaginary quadratic field.